com.github.chaosfirebolt.converter.ArabicParser Maven / Gradle / Ivy

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package com.github.chaosfirebolt.converter;

import com.github.chaosfirebolt.converter.constants.IntegerType;
import com.github.chaosfirebolt.converter.util.PairMap;

import java.util.Map;
import java.util.NavigableMap;

/**
 * Class used to parse strings in arabic numeral format to {@link RomanInteger}.
 *
 * @see Parser
 */
public final class ArabicParser extends BaseParser {

  /**
   * Constructs a new instance, providing the required {@link IntegerType}
   */
  public ArabicParser() {
    super(IntegerType.ARABIC);
  }

  @Override
  public RomanInteger parse(String number) {
    number = integerType.validateFormat(number.trim());
    int arabicValue = integerType.validateRange(Integer.parseInt(number));
    StringBuilder roman = new StringBuilder();
    NavigableMap arabToRoman = PairMap.getInstance().getArabicToRoman();
    for (int i = 0; i < number.length(); i++) {
      int digit = Integer.parseInt(Character.toString(number.charAt(i)));
      int power = number.length() - 1 - i;
      int exp = (int) Math.pow(10, power);

      int key = digit * exp;
      if (digit == 4 || digit == 9) {
        roman.append(arabToRoman.get(exp)).append(arabToRoman.higherEntry(key).getValue());
      } else {
        while (key > 0) {
          Map.Entry floorEntry = arabToRoman.floorEntry(key);
          int repeat = key / floorEntry.getKey();
          for (int j = 0; j < repeat; j++) {
            roman.append(floorEntry.getValue());
            key -= floorEntry.getKey();
          }
        }
      }
    }
    return new RomanInteger(roman.toString(), arabicValue);
  }
}